© 2018 American Chemical Society. Three geminal zwitterionic compounds are synthesized pursuing five parameters of green chemistry: atomic economy, environmental factor, mass intensity, mass reaction efficiency, and carbon efficiency; and evaluated as corrosion inhibitors for carbon steel (AISI-1018). The zwitterions are produced with variable length from amines (i.e., hydrocarbon chains), achieving mass reaction efficiencies higher than 80%, without the generation of wastes. The molecular structures are characterized using infrared spectroscopy and nuclear magnetic resonance. AISI-1018 steel coupons (blank corrosion) are used to test the corrosion inhibition of the geminal compounds at different concentrations (10, 25, 50, 75, and 100 ppm) in 1.0 M NaCl saturated with CO 2 (pH = 3.5 and 70 °C). Electrochemical characterization is conducted using the open circuit potential (OCP) method, and polarization curves (±320 mV vs OCP) to determine the optimum concentrations in which the inhibitors decrease the corrosion rate of the steel. The corrosion mechanism of the steel is performed under these selected conditions using electrochemical impedance spectroscopy. The components of impedance (Nyquist diagrams) increase as a function of immersion time, indicating the continuous adsorption of the inhibitors, and efficiency to considerably retard the corrosion of steel in these media. The best corrosion inhibition for low-concentration ranges is evaluated for 25 ppm LZW-B16 molecule, obtaining 1.0 × 10 -7 A·cm -2 , -0.66 V, 0.001 mmpy and 99.94% for corrosion current density and potential, corrosion rate and inhibition efficiency, respectively. Critical micelle concentration from surface tension for LZW-B16 corroborates the best performance around this concentration. Biodegradability tests conducted with LZW-B16 reveal its biodegradation by approximately 30% during 28 days of testing, which agrees with the environmental demands of the oil industry.
Juárez, E. G., Mena-Cervantes, V. Y., Vazquez-Arenas, J., Flores, G. P., & Hernandez-Altamirano, R. (2018). Inhibition of CO <inf>2</inf> Corrosion via Sustainable Geminal Zwitterionic Compounds: Effect of the Length of the Hydrocarbon Chain from Amines. ACS Sustainable Chemistry and Engineering, 17230-17238. https://doi.org/10.1021/acssuschemeng.8b04619